Chuck



Feb. 7, 1939.

R. L, HIBBARD lCHUCK Filed April 2, 1937 2 Sheets-Sheet 2 INVENTR.oeeverL. HIBBHRD f gff,UNITED STATES llli opens and closes the chuckjaws.

Patented Feb. .7', Y1939 if' PATENT OFFICE ,y l-cHUcir Y'Robert L.Hibbard, Pittsburgh, Pa., assigner of one-*half to William K. Stamets,Pittsburgh,

Application April 2, 1937, Serial No. 134,622

1 claim. (ci. 279-1) The invention relates to chucks of the powerrdriven type, and lparticularly to the manually operable means foropening andv closing the jaws f so as to clamp and unclamp the blankwhich is 55 'held and rotated by the chuck. One of the ob- 'l0 housing,and the operator may on occasion be under the mistaken impression thatthe applica- 'tion of power to the chuck has been discontinuedrvrvvhensuch is not the case, and attempt to operate the hand wheel orequivalent means which This involves throwing the hand wheel into gearwith the jaw operating means, and if the chuck is in rotation, the handwheel will be turned violently, sometimes with serious injury to theoperator. The

:2,0 kpresent invention provides Ymeans whereby such 4.an accidentisguarded against, the operating means for throwing the hand wheelr intogear ,with the chuck being so coordinated with a clamping'means. Afurther difficulty which arises with chucks of the kind above describedis the application of v30 too great clamping force by the jaws of thechuck which may deform a blank (such as a thin walled cylinder) andresult in improper machinling thereof. The present invention is designed.tof overcome this difficulty by the provision of v 35 means in the lineof connections between the yhand wheel or other turning device whichscrews Vthe jaws in of such character that only a prel determined forcecan be applied to the blank by the jawsregardless of the force appliedto the 40Vturning device. This is accomplished by a friction clutch inthe train'of connections, in cone junction with a positive drive in thereverse direction, so that no difficulty will be encountered inreleasing the blank despite the presence of the 45 friction clutch. Oneembodiment of the invention is illustrated in the accompanying drawings,

wherein: Y

l Figure 1 is a, perspective View of a cylinder bor- 1 ing machineequipped with the improved clutch 50 operating mechanism. Fig. 2 is avertical section through the chuck and operating means. Fig.

3 is a section on the line III-III of Fig. 2. And

' Fig. 4 is a diagrammatic view showing the wiring arrangement.

5 having at one end a housing 6 for the chuck which carries the blank 1to be machined; a carriage 8 movable longitudinally of the machine andcarrying the tool Vwhich bores out the blank; means in the casing formoving the carriage back 5 `and forth; a loadingtable 9 for supportingthe blanksin the loading and unloading operations; facing tools on eachside of the chuck housing which are of no moment in so far as theinvention here is concerned; the hand wheel I mount- -l0 ed on thechuckv housing and serving to move the chuck jaws in and out, as laterdescribed; the handle. Il which cooperates with the switch I2 Yand givessafety control of the operation of the hand wheel; and a motor I3 (Fig.2) located '15 in or adjacent to the base casting and serving to rotatethe chuck.

The general chuck structure is well known in the art, andY comprises aframe member I4 mounted for rotation in the housing 6 on the 1.20 rollerbearings I5 and provided with sleeve portions I6 through which the stemsIl of the three chuck jaws I8 extend. The frame has bolted to one sidethe ring I9 having the spur teeth 20 varound its periphery. The ring isdriven by the ,25

spur pinion 2I on the shaft 22 which is driven from the motor I3 throughsuitable reduction gearing.

The stems Il of the chuck jaws are slidable vthrough sleeves I6 and arethreaded internally 30 to receive the shafts which are swivelled attheir outer ends, as indicated at 26. The outer ends of the shafts 25have the bevel pinions 2l secured thereto and mesh with the gear 28which is in the form of a ring journalled on a hub 29 integral with thechuck frame. The ro- Vtation of this gear 28 on its hub provides for therotation of the shafts 25 and the movement of the jaws of the chuck inand out.

The ring 28 is also provided with spur teeth 30 40 around its peripherywhich engage a pinion 3I on the shaft 32 to the outer end of which thehand wheel I0, heretofore referred to, is attached. 'Ihe shaft 32 ismounted for sliding endwise movement on the hub 33, and when in theposition shown, the rotation of the shaft will move the chuck jaws in orout, depending on the direction of the rotation. To disengage the pinion3| from driving relation'with the teeth 30, the shaft is moved to theleft. Safety means are provided for locking the shaft in disengagedposition inthe form of the groove 34 and cooperating pin 35 which dropsinto the groove when the groove is in alinement therewith.

The pin 35 is pivoted to one arm of the lever 36 55 (Figs. 1 and 4)whose other arm is supported on the chuck housing by means of the link31. The lever is provided with a handle II, heretofore referred to,which when swung so as to lift the pin 35, engages the handle 38 of theswitch I2 and moves it to open position. This movement interrupts theelectric circuit through the motor I3 (Figs. 2 and 4) which rotates thechuck. Since the shaft 32 can not be moved to the right to engage thepinion 3I with the gear teeth 30, until the pin is lifted and theelectric circuit interrupted at the switch I2, the operator is protectedfrom inadvertently bringing the hand wheel I and driving connectionsinto gear with the chuck while the chuck is being driven by the motor.The circuit for controlling the operation of the motor I3 from theswitch I2 will be seen by reference to Fig. 4. The motor lies in acircuit including the relay bar 39 and wires 40 and 4 I. The winding 42of the relay lies in a circuit including the wires 42, 43 and 44 and theswitch I2. When l'through the coil 42a of the relaywhich opens,

interrupting the motor circuit. .When the handle II is swung to theright incident to the pin 35 being allowed to move into the groove 34,the switch handle 38 moves to the right permitting the closing of theswitch and energizing the relay winding 42a so that the bar 39 moves toclosing position completing the motor circuit. A push button 45 is alsoprovided in the relay circuit to permit starting and stopping of themotor from a convenient position at one side of the machine.

In order to prevent the chuck jaws from` being clamped upon the blankwith such force as to distort it, a slip connection is provided betweenthe hand wheel I and the shaft 32, as illustrated in Fig. 2. Keyed tothe shaft is a sleeve 45a, and on the sleeve is rotatably mounted thehub 46 of the hand wheel. The sleeve 45a has integral therewith a flange4l lying on one side of the hub 46, and on the opposite side of the hubis a plate 48, friction rings 49 and 5I) being interposed between theplate and hub and between the hub and the flange 41. The plate is keyedto the shaft 32 and is pressed to the right by the nat spring I placedunder tension by the nut 52 threaded to the end of the shaft. Thisarrangement provides a friction slip connection between the hand wheeland the shaft 32, so that only a limited and predetermined clampingforce can be applied by the chuck jaws to the blank held thereby.

In order to provide for a positive connection between the hand wheel andthe shaft 32, so that the eifect of the slip connection is avoided onthe reverse movement of the hand wheel, a pawl 53 is pivoted in a recessin the sleeve 45 and held in the position shown in Fig. 3 by a spring54. The end of the pawl is engaged by one of the three teeth l55 on thehub 4S of the hand wheel when such wheel is .turned in acounterclockwiseI direction (Fig. 3) to release the chuck jaws. It willbe seen that the arrangement, as described and illustrated, provides afriction slip connection for tightening the chuck jaws when the handwheel is turned in one direction and a positive connection for releasingthe jaws when the wheel is turned in the reverse direction.

What I claim is: y

In a machine tool having a chuck with movable jaws, gearing for movingthe jaws in and out, an electric drive for rotating the chuck, a switchcontrolling said drive, and a hand operated shaft mounted for 'endwisemovement carrying a gear and adapted in one position of endwise movementto bring said gear into driving engagement with said gearing and inanother position of endwise adjustment to disengage the gear from saidgearing, said shaft being provided with a circumferential groove, meansfor maintaining said switch in open position comprising a locking pinmounted for sliding movement transversely of sadshaft normally pressedtoward the shaft and adapted to move into the groove and lock it againstendwise movement .when the shaft is brought to inoperative position withits-gear disengaged-from said gearing, and hand operated means forwithdrawing the pin from the groove positioned so as to engage theyswitch and open it when the pin is so withdrawn.

ROBERT L. HIBBARD.

